api: add a basic health checking endpoint

api/health.go

@@ -0,0 +1,17 @@
+package api
+
+import (
+	"net/http"
+
+	"github.com/labstack/echo"
+	"github.com/tsuru/cst/db"
+)
+
+func health(ctx echo.Context) error {
+
+	if db.GetStorage().Ping() {
+		return ctx.String(http.StatusOK, "WORKING")
+	}
+
+	return ctx.String(http.StatusInternalServerError, "DOWN")
+}

api/health_test.go

@@ -0,0 +1,57 @@
+package api
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/tsuru/cst/db"
+
+	"github.com/labstack/echo"
+	"github.com/stretchr/testify/require"
+)
+
+func TestHealth(t *testing.T) {
+
+	t.Run(`When system is unhealthy, should return 500 error`, func(t *testing.T) {
+
+		db.SetStorage(&db.MockStorage{})
+
+		e := echo.New()
+
+		request := httptest.NewRequest(http.MethodPost, "/", strings.NewReader(``))
+
+		recorder := httptest.NewRecorder()
+		context := e.NewContext(request, recorder)
+
+		health(context)
+
+		require.Equal(t, http.StatusInternalServerError, recorder.Code)
+		assert.Equal(t, "DOWN", recorder.Body.String())
+	})
+
+	t.Run(`When system is working, should return 200 code`, func(t *testing.T) {
+
+		storage := &db.MockStorage{
+			MockPing: func() bool {
+				return true
+			},
+		}
+
+		db.SetStorage(storage)
+
+		e := echo.New()
+
+		request := httptest.NewRequest(http.MethodPost, "/", strings.NewReader(``))
+
+		recorder := httptest.NewRecorder()
+		context := e.NewContext(request, recorder)
+
+		health(context)
+
+		require.Equal(t, http.StatusOK, recorder.Code)
+		assert.Equal(t, "WORKING", recorder.Body.String())
+	})
+}

api/server.go

@@ -36,6 +36,8 @@ func (ws *SecureWebServer) Start() error {
 	ws.echo.Use(middleware.Recover())
 	ws.echo.Use(middleware.Logger())
 
+	ws.echo.GET("/health", health)
+
 	v1 := ws.echo.Group("/v1")
 	v1.POST("/scan", createScan)
 	v1.GET("/scan/:image", showScans)